1. Field of the Invention
The present invention relates to the preparation of polychlorophosphazene by polycondensation of N-(dichlorophosphoryl)trichlorophosphazene.
2. Description of the Prior Art
It is known to this art (published European patent application No. 0,026,685) to prepare linear polychlorophosphazenes by the polycondenstion of N-(dichlorophosphoryl)trichlorophosphazene according to the following reaction scheme: ##STR2##
Compared to the process described in U.S. Pat. No. 3,370,020 (which employs a hexachlorocyclotriphosphazene starting material), the process described in the noted '685 European application enables production of non-crosslinked polymers of high molecular weight from readily available monomers, while controlling the molecular weights at the levels desired.
The process described in the '685 European application is generally carried out at a temperature of from 240.degree. to 350.degree. C. for 8 to several tens of hours, depending on the level of molecular weight desired.